For a pretty alien
by Rumbelleforever64
Summary: Based on a post by .In the year 2017, Kara Zor-El is lured to save her sister from an evil secret organisation. The kidnapping is a ploy to unleash red kryptonite on Kara and have her destroy National City. Rip Hunter sets a course to the future of Kara's Earth and sends Sara to deal with the problem.
1. Chapter 1

**Based on a Tumblr Post by Supercanaries:** post/151156574056/supergirl-dcs-legends-of-tomorrow-au-in-the

 **In the year 2017, Kara Zor-El is lured to save her sister from an evil secret organisation. The kidnapping is a ploy to unleash red kryptonite on Kara and have her destroy National City. However, when Kara accidentally kills Alex, the darkness inside her grows exponentially until she destroys all Earths. Rip Hunter sets a course to the future of Kara's Earth and sends Sara to** **deal** **with Supergirl, both because she understands being devoured by darkness and because she relates to losing a big sister. Instead of letting Alex die, though, Sara decides to go save her in Kara's place.**

* * *

 **Chapter 1**

"What's the emergency Rip?" Asked Sara as she entered the room. She had no idea why Rip had summoned her in here, only her, or what he wanted but he did not look happy. Rory was stood beside him, looking annoyed as usual. "You got a solo job." He said, "Some alien chick destroying stuff."

"Wait, what?" Asked Sara, now extremely confused.

"Gideon, show her." Ordered Rip.

The image of an undeniably beautiful woman in a black jumpsuit appeared on the screen and Sara fought the urge to flinch. She was laughing in a way that made Sara afraid. An angry, hate-filled, yet somehow gleeful laugh. Then there were gunshots and...oh crap those bullets just shattered on her. Her features solidified into, what could only be described as pure rage, and she lunged out of frame.

"Meet Kara Zor-El, known on her Earth Kara Danvers." Explained Rip, "A Kryptonian who was sent away as her planet was destroyed. She ended up a hero named Supergirl, but in 2017, an organisation kidnapped her foster sister, Alex. While trying to save her, she was exposed to a substance named Red Kryptonite, which massively enhanced her rage. As she attempted to destroy the base, she accidentally destroyed a support beam and Alex was crushed. When she realised her sister was dead, the darkness in her grew, to the point where she destroyed, not just her Earth, but all Earths." Rip commanded Gideon to shut down the image as cries of agony filled the room. "Your mission is to stop Miss Danvers from trying to save her sister. If she does, Alex will die and Kara will destroy everything."

"Aliens," Scoffed Rory, rolling his eyes, "I hate aliens."

Sara considered everything she's just been told. Rip wanted her to stop an alien. A pretty, seemingly invulnerable alien who was capable of destroying everything.

"Why me?" She asked, "She could probably kill me in 5 seconds flat; why send me?"

"Because you understand." Said Rip, gently, "You know how it feels to have the darkness consume you and, more importantly, you know how it feels to lose a sister." Sara froze before slowly backing towards the door.

"Are you saying that you want me to go to this girl's Earth, let her sister die and deal with the fallout?"

"Not at all Miss Lance. I'm saying, you stop HER from doing the saving." Rip sighed and walked over to the assassin, placing his hands on her shoulders, "There is no-one I would trust more with this one Sara." Sara stared at him for a moment, before giving up and strapping herself in.

 _This is not gonna go well._

* * *

 _D.E.O Headquarters_

Kara was pacing in the center of the HQ. J'onn was honestly starting to worry about her wearing a hole into the floor. To Kara, however, it didn't matter; nothing mattered because Alex wasn't here. It should have been a simple mission, how did she let that happen?! They'd taken the bad guy out (with Kara commenting that he "took more punching than usual") and Alex had escorted him into a D.E.O van while Kara went to deal with a fire in the centre of the city. It was less than ten minutes later that J'onn had called her and told her the van was abandoned, the other agents were dead and Alex had disappeared.

"Supergirl." Kara froze and her glare fixated on one of the tech guys. He visibly shrunk under her gaze, clearly worried about being vaporized. "I-I received an e-mail. It says they'll reveal Agent Danvers' location tomorrow, along with instructions."

"That's all you've got!" She took two steps towards him before J'onn grabbed her arms and dragged her out of the room.

"Kara, there is nothing we can do. The whole organisation is looking for her, but the best thing you can do right now is go home. Go to CatCo, do work and leave our guys to do their jobs."

"But..." Kara tried to protest but the Martian just held his hand up.

"If the e-mail is telling the truth, we won't get any exact information until tomorrow and you still need to keep up appearances." He placed his hands on her shoulders gently, "We'll find her Kara, I promise." Kara sighed and angrily wiped the tears from her eyes.

Kara left the HQ and headed towards CatCo. Work may have been the last thing on her mind, but J'onn was right, she wasn't much use until they knew Alex's exact location, so she figured overtime planning the press party was as good as anything else. The closer she came to the building, however, the more tears started to prick her eyes and the more hopeless she felt. Eventually, she changed direction heading to her apartment as fast as she could without using super speed. Closing and locking the door, Kara ran into her bedroom, collapsed onto the bed and began to sob. She needed Alex. How could she have let it happen?

Cheerful music rang out within the room, causing her to look up. Her phone, carelessly discarded on the bedside table, was ringing obnoxiously loudly. With a groan, she reached over and grabbed it, wiped her eyes and answered it. _"Kiera, is everything ready for the party tomorrow?"_ Kara sat up immediately, sniffing slightly before replying, "Um, almost Ms Grant, I have to call the DJ first thing to confirm the set list, but everything else is ready."

 _"Excellent, I expect to see you there, no excuses."_ Before she could reply, Cat hung up and Kara fell back onto the bed, running a hand over her face.

 _Things cannot get any worse..._


	2. Chapter 2

**Okay, first off, I AM SO SORRY! I've been buried under revision for my mock exams (which will be happening for the next 2 weeks, please bare with!) and then I lost my draft so this took a freakin' long time. Still, thank you so much for** **the comments, they've been really nice to read and I'll try to find a way to make a good upload schedule.**

* * *

"Run that by me one more time Gideon."

Sara stood in the fabricator room, trying to find a good dress while Gideon gave her the load down on Supergirl. Rip had told her that she should go to a press party for a company called CatCo and do some recon on/possibly meet Kara, a prospect that was both exciting and slightly concerning to the assassin.

 _"Kara Zor-El Danvers, 24 years old. Last daughter of the planet Krypton, cousin to Kal-El, known on Earth as Superman or Clarke Kent. Assistant and junior reporter at CatCo. Worldwide Media. Abilities: Superspeed, hyper sense of hearing, x-ray sight, focused heat vision, cryogenic breath, invulnerability and super strength."_

"How strong equals super strong?" Asked Sara, briefly glancing at the light blue dress in the mirror before deciding against it.

 _"I can't find any record of her exact strength, but there are reports of her lifting a space station out of the atmosphere."_

Sara froze, mid-twirl. "An actual space station?!" She muttered under her breath, "How the Hell does Rip expect me to stop her from doing anything?!" Sighing, she settled on an emerald green dress with a gold purse. For her own peace of mind, she grabbed four knives and put them in the purse. She then took the invite that Gideon had perfectly forged and looked over it again. "What's the party for again?"

 _"Cat Grant won an award for an article on Supergirl's quote "heroic and daring" feats. Miss Danvers organised the party."_

* * *

 _CatCo Media party, National City._

Kara nervously fiddled with the bridge of her glasses, a habit she'd had for years, as she made her way through the crowd of guests. She really did not want to be here, she would rather be anywhere that wasn't here, but Cat had threatened to fire her and J'onn had waved some Kryptonite cuffs at her when she tried to convince him to get her out of it. Forcing a smile, she approached Cat, trying to look somewhat happy to be there. "Ms Grant." Cat turned to her, a subtle glare fixing on her features, alerting Kara to the fact that the smile was not convincing enough.

"Kiera, is there a problem?" Kara felt herself shrink under the intense gaze and shook her head meekly. Cat sighed, "Don't lie Kara, you're awful at it." For a moment, Kara considered telling Cat everything, but the only words out of her mouth were;

"My mind's not really here, Ms Grant."

"Well, get it here, I need you 100% focused tonight or not here, understood?"

"Yes, Ms Grant." Kara quickly walked away from Cat and made her way over to the bar, even if she couldn't get drunk, maybe the taste would help distract her. As she sat down, she noticed a very beautiful woman sat two seats away looking at her. The woman had long blonde hair, stunning eyes and was slightly shorter than herself. Her emerald dress almost reached the floor and showed her figure off brilliantly. Turning back to the bartender, Kara ordered her drink and allowed herself to slouch. She couldn't do this. She couldn't act like everything was perfect and normal when Alex wasn't safe.

"Rough day?" The voice startled her out of her trance and caused her to turn around. The pretty blonde was now next to her, looking at her sympathetically. Kara felt her heart stop for a moment and her brain seemed to lose any ability to form coherent sentences. "Name's Sara, Sara Lance. And you?"

Kara managed to snap herself out of it and took Sara's extended hand. "Kara Danvers. It's nice to meet you, Miss Lance." Sara laughed quietly and Kara's brain turned to mush again at the sound.

"Please, call me Sara. It's nice to meet you too Kara."

Before Kara had any opportunity to reply, her phone buzzed in her purse. "Sorry, one second." Sara smiled at her sweetly and Kara was almost certain she was blushing. Her face set into a glare however as she read the text.

 _They've sent us a message. Get to the D.E.O, now._

 _J'onn._

"I have to go." Said Kara, suddenly, standing slightly faster than a normal human. "Family stuff, I'm sorry. It was lovely to meet you, Sara." With that, the Kryptonian practically ran out of the room, leaving Sara in an awed state behind her.

 _How in the Hell could she turn into the woman I saw?_


	3. Chapter 3

***Peeks out from behind a shield, holding a tiny white flag* I'm not dead! I am SO SORRY that this took so long, between my internet hating me, mock exams, and prep for actual exams (GCSEs are a bitch!) I haven't had the time, nor the chance to just sit down and write. I'm going to try and get the updates up more regularly but, rest assured, I am not giving up on this story.**

* * *

 _D.E.O HQ_

"What is it J'onn?" Asked Kara, frantically, as she sprinted into the HQ. "You said they'd sent a message?"

J'onn turned to face her, silently hoping she'd listen to him after he spoke.

"She's in a warehouse down by the industrial district. We scanned the area around it and it revealed a large radioactive signal...KARA!" Apparently, his silent hopes were useless as the Girl of Steel was already striding towards the exit. "Kara, we need to wait until we know what's in there This could be a trap for all you know!" He called after her. She froze at the door. J'onn sighed and put his hand on her shoulder. "I know you're worried Supergirl. All of us are, but diving in, head-first, could get you killed! Alex wouldn't want that, and you know it."

Kara ran a hand through her hair, her brow crinkled. She pulled away from the Martian.

"Yes, I know that, but a lack of info and the promise of danger have never stopped her from helping or protecting me. She's my sister J'onn! I can't just wait around and give them a chance to kill her." He tried to run after her, but she's already taken off, disappearing into the night sky.

* * *

 _Waverider_

Sara was sat in her room, her costume on, reading through on of Kara's articles. The rest of the Legends had gone to explore National City, Rip having parked Waverider at the very edge of the industrial district, and Sara had decided to do some research on her target. She had to admit, it was very well written and extremely balanced. _I'm impressed,_ she thought to herself. It still baffled her that the girl, who seemed shy, yet strong at the party, and who appeared nothing short of cheery in her writing, could turn into the cold murderer that Rip had shown her.

 _"Miss Lance?"_ Sara was startled out of her silence by Gideon.

"What is it?"

 _"Supergirl is flying towards the building containing Alex Danvers. Her ETA is approximately two minutes."_ The blonde jumped off her bed and ran towards the ship's exit.

* * *

As Kara landed, she took stock of the area around her. It seemed abandoned, probably due to the late hour, and she couldn't see anything untoward. Using her x-ray vision, she scanned each building until one caught her eye...or rather, didn't. She couldn't see inside, almost like it was... _lead-lined,_ she thought, _I'm coming, Alex._

The sound of footsteps caught her ear and she turned suddenly. It was the woman from the party, this time in a white ( _was that leather?_ ) jacket and pants, a large staff in her hand and her blonde hair cascading down her shoulders. Kara had to admit, the woman was beautiful, but the way she was looking at Kara...like a threat, made her angry. _She's with them._

"As pretty as you are destructive." Said Sara, casually. She meant it. Kara Danvers had been pretty yes, but _Supergirl?_ Supergirl was hot. _Maybe it's the suit,_ she thought. Kara stepped towards her and Sara tensed, _or maybe it's because she's terrifying._

"They send you out here to stop me? Because I'm really not having a good day and I'd hate to mess up that face." Her voice was harsh, but Sara could hear the pain behind it. Quickly pulling her staff apart into batons, she placed them in the holders by her sides and put her hands up.

"I don't want a fight."

"Then don't try to stop me." Another step forwards for Kara and Sara felt herself shiver under the hero's intense glare.

 _Heat vision, Lance. Do NOT piss her off._

"I'm not with them. I'm here to help." That got the other woman's attention. Sara took a cautious step forwards, "I know about your sister and I know how badly you want to help her, but I can't let you go in there. If you go in, she'll die." The glare turned slightly red and Sara's eyes widened.

 _Remember what we said about NOT pissing her off?_ her brain taunted.

"Is that a threat Miss Lance?" Spat Kara.

"Not at all." Began Sara, her tone becoming softer, in an attempt to quell the hero's nerves, "But I know what happens if you go in there and I'm not going to let it happen."

"What do you mean, you know what happens?" Kara turned her head slightly, her eyes normal again and Sara found herself picturing a puppy instead of an alien that could melt her face off. She sighed and lowered her hands.

"Kara Zor-El," The alien's eyes widened at the use of her real name, "If you try to save your sister, you will be responsible for her death and the death of your Earth."


	4. EXAMSS!

I AM SO BLOODY SORRY! I'VE HAD EXAMS AND THEY ARE KILLING ME AND GCSES SUCK, DO NOT DO THEM! *sigh* Okay, got that out of my system. For real, I'm so sorry about how long this is taking, but I now have a plan! The latest this story will be updated is JUNE 21st, I promise. Thanks to everyone still reading and the updates are coming, I swear.

This has been my public apology.


	5. Chapter 4 (Finally)

_D.E.O. Headquarters_

"So...you're from the same Earth as The Flash?" Asked Winn, curiously. Sara nodded. Having convinced Kara to at least hear her out, the Kryptonian had promptly dragged her ass back to the DEO and ordered her to explain. Now, the assassin was sat in, what she assumed, was a briefing room with an all-too-curious tech guy, a stoic-faced man and an extremely sceptical looking Kara. "And your boss wants you to stop Supergirl saving Alex, or we're all dead?" Sara nodded again, though she couldn't quite tune out Kara's scoff from the corner.

"C'mon Winn," the hero groaned, clearly not buying Sara's story, "She's obviously just trying to keep me away from Alex! I mean seriously, I couldn't destroy Earth, it's my home!" Sara groaned and slammed her head onto the table.

"That's what I've been saying! This whole thing is a trap, they WANT you to storm in and try to save your sister so they can infect you with that red...whatever-the-Hell you call it..."

"Kryptonite." Came the resounding reply, causing the assassin to roll her eyes.

"But it doesn't work out like that, right?" Sara looked at Winn, then to Kara and back again with a sigh.

"No. In the future Rip showed me, Kara went insane and destroyed the complex, then your Earth."

"You said I'd be responsible for Alex's death. You can't keep me here Miss Lance, so let me go and save my sister!" Snapped Kara, taking a step towards Sara. Sara stood, her frustration at the annoyingly adorable, if completely unreasonable and stubborn alien, finally boiling over.

"You are responsible, Miss Danvers," She seethed, her voice a deadly calm that made even J'onn shiver, "The complex collapses and Alex is crushed. YOU kill her. And the grief and the red stuff drive you mad. You destroy your Earth and become a threat to every other one, including mine." Kara's face fell with every word that left Sara's mouth, the fight visibly melting out of her and Sara immediately felt terrible.

Kara's face fell with every word that left Sara's mouth, the fight visibly melting out of her as she lowered herself into a chair. For a moment, she couldn't help but see herself in Kara's eyes. If she had the chance to save Laurel and someone was telling she couldn't...actually, they already had done that and it felt horrible. Sara sighed and ran a hand through her hair.

"Look," She began, her voice much more relaxed, "I know exactly how you feel. Really, I get it," She said, as she moved to sit next to Kara, "And like you said, I can't stop you from doing anything. Bu if you go, your Earth will die by your hand."


End file.
